check if this chick will develop tail at 4 weeks. the comb is big but leghorns do have big combs. as I have fun with a mystery chicken that had big comb and wattles and looks like a girl (at 4 months I am still not sure) I advise you to wait. girls usually develop tail at 4 weeks (not a rule). after that both sexes have tails, so don't forget to check it at 4 weeks exactly. btw, the comb looks like it will be floppy and girls only have floppy combs. the chick is too young to be sure.